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In statistics, the phi coefficient (or mean square contingency coefficient and denoted by φ or r φ) is a measure of association for two binary variables.. In machine learning, it is known as the Matthews correlation coefficient (MCC) and used as a measure of the quality of binary (two-class) classifications, introduced by biochemist Brian W. Matthews in 1975.
Phi is related to the point-biserial correlation coefficient and Cohen's d and estimates the extent of the relationship between two variables (2 × 2). [32] Cramér's V may be used with variables having more than two levels. Phi can be computed by finding the square root of the chi-squared statistic divided by the sample size.
In statistics, Cramér's V (sometimes referred to as Cramér's phi and denoted as φ c) is a measure of association between two nominal variables, giving a value between 0 and +1 (inclusive). It is based on Pearson's chi-squared statistic and was published by Harald Cramér in 1946.
Unweighted sample sizes (counts). ... A simple measure, applicable only to the case of 2 × 2 contingency tables, is the phi coefficient (φ) defined by
Instead, measures such as the phi coefficient, Matthews correlation coefficient, informedness or Cohen's kappa may be preferable to assess the performance of a binary classifier. [10] [11] As a correlation coefficient, the Matthews correlation coefficient is the geometric mean of the regression coefficients of the problem and its dual.
where = / is the proportion of the sample in cell (,). This is the empirical value of T . With χ 2 {\displaystyle \chi ^{2}} the Pearson chi-square statistic , this formula can also be written as
People with high blood pressure who slept for shorter durations were more likely to show poor cognitive function and increased levels of markers of brain aging and injury, a new study has found.
Coefficient of colligation - Yule's Y; Coefficient of consistency; Coefficient of raw agreement; Conger's Kappa; Contingency coefficient – Pearson's C; Cramér's V; Dice's coefficient; Fleiss' kappa; Goodman and Kruskal's lambda; Guilford’s G; Gwet's AC1; Hanssen–Kuipers discriminant; Heidke skill score; Jaccard index; Janson and Vegelius ...